---
title: "RAM Memory Expansion"
id: "34115"
type: "page"
slug: "ram-memory-expansion"
published_at: "2020-11-11T19:33:32+00:00"
modified_at: "2025-03-13T01:20:53+00:00"
url: "http://localhost/products/hardware/ram-memory-expansion/"
markdown_url: "http://localhost/products/hardware/ram-memory-expansion.md"
excerpt: "While resourceful owners could accomplish a lot with the 1K or 2K of RAM built in to their computers, more serious uses required more RAM. A huge number of expansion RAM packs were produced for the Sinclair computers."
---

While resourceful owners could accomplish a lot with the 1K or 2K of RAM built in to their computers, more serious uses required more RAM. Sinclair and Timex offered 16K RAM units for the ZX80, ZX81 and TS 1000 computers. For many, that was enough.

A huge number of expansion RAM packs were produced for the Sinclair computers. Some extended beyond the default 16K, others claimed to address the “RAM pack wobble” problem and others made RAM available in special locations or configurations or had other special features.

| Name | Description | Computers |
| --- | --- | --- |
| 1-3K Memory ExpansionHaven Hardware | Uses static RAM. | Sinclair ZX80 |
| 16-32-48K expanda RAMDancer | Fits inside case. | Timex/Sinclair 1000 |
| 16K or 32K RAM PlansT. W. Cook | Plans to expand 1K model to 16K or ZX81 with 16K to 32K for under $30. Fits inside ZX81. | Sinclair ZX81, Timex/Sinclair 1000 |
| 16K RAMSinclair Research Ltd. |  | Sinclair ZX80, Timex/Sinclair 1000 |
| 16K RAMSinclair Place | Gold-plated connectors and power LED. Manufactured by Indescomp. | Timex/Sinclair 1000 |
| 16K RAM (internal)DK'tronics | Internal RAM expansion for keyboard. | Timex/Sinclair 1000 |
| 16K RAM PackNamal Associates | No enclosure RAM pack. | Timex/Sinclair 1000 |
| 16K RAM PackDolphin Computer |  | Timex/Sinclair 1000 |
| 16K RAM PackAudio Vision |  | Timex/Sinclair 1000 |
| 16K RAM PackSuntronics |  | Timex/Sinclair 1000 |
| 16K RAM PackGladstone Electronics |  | Timex/Sinclair 1000 |
| 16K RAM PackCompu-Pak | Expansion for the Compu-board system. | Timex/Sinclair 1000 |
| 16K RAM PackDK'tronics | Available with or without a case. | Timex/Sinclair 1000 |
| 16K RAM PackJRS Software |  | Timex/Sinclair 1000 |
| 16K RAM PackKB Enterprises |  | Timex/Sinclair 1000 |
| 16K RAM PackKayde Electronic Systems Ltd. | Works on Sinclair power supply. | Timex/Sinclair 1000 |
| 16K RAM PackLaserscan Electronics Corp. | Highly crash resistant RAM pack that can be mounted inside the computer under the keyboard or plugged into the rear connector. Requires no extra power supply; comes with a special high pressure edge connector. | Timex/Sinclair 1000 |
| 16K RAM PackGround Control | Injection molded plastic case; overcomes wobble and disconnection problems characteristic of other units; optional extra is a keyboard sounder giving audible feedback when a key is pressed. | Timex/Sinclair 1000 |
| 16K RAM PackComputer Add-Ons | RAM pack physically similar to TS 1016. Claims not to suffer from wobble. | Timex/Sinclair 1000 |
| 16K RAM PackRKL Systems | Expandable to 32K. | Sinclair ZX80, Timex/Sinclair 1000 |
| 16K RAM plus Expansion BoardComp Shop, Ltd. | 3 slots with extra power supply. 4K or 16K. | MicroAce |
| 1K RAM BoardQuicksilva | Static RAM; expands internal memory to 2K. | Sinclair ZX80 |
| 256K RAM diskAERCO | Upgrade to disk interface. Can be configured as RAM disk or port-mapped in 64K banks shadowing the cartridge bank. | Timex/Sinclair 2068 |
| 2K Memory UpgradeCosmonics | Kit to increase the ZX81 to 2K. | Sinclair ZX81 |
| 2K RAM BoardQuicksilva | Static RAM; expands internal memory to 3K. | Sinclair ZX80 |
| 2K RAM PackDK'tronics | Static RAM expansion; works with built-in RAM. | Sinclair ZX80, Sinclair ZX81, Timex/Sinclair 1000 |
| 2K RAM UpgradeMicro Logic Corp | Upgrade for 1K ZX81. Includes 2K RAM chip, socket, jumper and instructions. | Sinclair ZX81 |
| 2K RAM UpgradePowertronix Electronics | Internal upgrade; replaces existing RAM chips. | Sinclair ZX81 |
| 2K to 24K Memory ExpansionJST Enterprises | Plans to expand memory up to 24K, using 2K RAM chips, placed anywhere from 8192 to 32768. | Timex/Sinclair 1000 |
| 32K and 32K/64K Non-Volatile Memory RAM Board/CartridgesThomas B. Woods | Plugs into the TS2068 cartridge slot. On board battery keeps it alive even when you turn the computer off. Switch selectable for use in the DOCK or EXROM banks with no mods to the computer. Write protect switch lets you use memory like an EPROM. Run your own plug-in BASIC programs. Detailed instructions include utilities | Timex/Sinclair 2068 |
| 32K Internal RAM ModificationZunk Custom Electronics | 32k RAM inside the 2068, in the upper half of the DOCK and EXROM bank. RAM is active in the DOCK and/or EXROM bank, allowing user to save files that reside in the DOCK bank. Can also load files directly into this RAM from tape. Switch to disable the RAM in the DOCK bank so | Timex/Sinclair 2068 |
| 32K RAMSinclair Place | Gold-plated connectors and power LED. Manufactured by Indescomp. | Timex/Sinclair 1000 |
| 32K RAM cartridgeLemke Software Development | Expansion RAM, plugs into dock slot. | Timex/Sinclair 2068 |
| 32K RAM PackRKL Systems | Expandable to 64K. RKL joystick systems can be added to this unit. | Sinclair ZX80, Timex/Sinclair 1000 |
| 32K RAM Piggy-BackGladstone Electronics | Can be used standalone or with a 16K RAM for a total of 48K. | Timex/Sinclair 1000 |
| 3K RAM BoardQuicksilva | Static RAM; expands internal memory to 4K. | Sinclair ZX80, Sinclair ZX81, Timex/Sinclair 1000 |
| 48K Memory ExtensionMemotech | Allows ZX81 to run 48K Basic programs including up to 16K of assembly code. ZX81 sits on custom built case containing the Memotech. | Sinclair ZX81, Timex/Sinclair 1000 |
| 48K RAM for TS2000Computer Add-Ons | Announced before 2068 launched. Manufacturer assumed 2068 would be identical to Spectrum. | Timex/Sinclair 2068 |
| 48K RAM PackRKL Systems |  | Sinclair ZX80, Timex/Sinclair 1000 |
| 4K RAM PackDK'tronics | Static RAM expansion; works with built-in RAM. | Sinclair ZX80, Sinclair ZX81, Timex/Sinclair 1000 |
| 64K Dynamic RAMJohn Oliger Co. | 64K DRAM board for the TS1000, TS1500 or ZX81. Special features of this memory include: 8-12K on/off switch 12-16K on/off switch two banks of 8K ram available mapped 8-16K (Bank A/B switch) and 48-64K on/off switch | Timex/Sinclair 1000 |
| 64K RAMSinclair Place | Gold-plated connectors and power LED. Manufactured by Indescomp. | Timex/Sinclair 1000 |
| 64K RAM (internal)DK'tronics | Internal RAM expansion for keyboard. | Sinclair ZX81 |
| 64K RAM PackCompuTech & Software Industries, Inc. |  | Sinclair ZX80, Sinclair ZX81, Timex/Sinclair 1000 |
| 64K RAM PackNamal Associates | No enclosure RAM pack. 4K pages can be switched off. | Timex/Sinclair 1000 |
| 64K RAM PackDolphin Computer |  | Timex/Sinclair 1000 |
| 64K RAM PackAudio Vision |  | Timex/Sinclair 1000 |
| 64K RAM PackDK'tronics | Available with or without a case. 8-16K area available. | Timex/Sinclair 1000 |
| 64K RAM PackGladstone Electronics | Metal case, snug fit for no wobble. | Timex/Sinclair 1000 |
| 64K RAM PackCompu-Pak | Expansion for the Compu-board system. | Sinclair ZX81, Timex/Sinclair 1000 |
| 64K RAM PackBARLOG Software |  | Timex/Sinclair 1000 |
| 64K RAM PackSuntronics |  | Timex/Sinclair 1000 |
| 64K RAM PackJRS Software |  | Timex/Sinclair 1000 |
| 64K RAM PackSunflower Systems | Self-contained memory expander, housed in metal. | Timex/Sinclair 1000 |
| 64K RAM PackComputer Add-Ons | RAM pack similar in shape to the TS 1016. Claims not to suffer from wobble. | Timex/Sinclair 1000 |
| 64KT/64KZIndependence Research | 64K RAM upgrades which mount inside the TS 1000 or ZX81. Installs in a minute with no soldering, and easy to follow instructions. Disable the 10-12K, 8-12K, or 8-16K areas of memory with a switch. Models specific to the ZX81 and TS 1000. | Sinclair ZX81, Timex/Sinclair 1000 |
| 6K memory (internal)Zodex | Add 4K or 6K RAM internally. | Timex/Sinclair 1000 |
| 8K RAM packDK'tronics |  | Timex/Sinclair 1000 |
| Add on RAM for ZX80 instructionsDennis Weber | Complete schematic, parts list, sources, and how-to. | Sinclair ZX80 |
| Complete Memory PlansSpectra Computer Products | Documentation packet that covers memory pack troubleshooting. Includes plans for constructing your own memory pack, EPROM reader and extending the memory of the 16K RAM pack up to 64K. | Timex/Sinclair 1000 |
| CRAMIC-81Cambridge Microelectronics | 16K RAM pack using CMOS 6116 static RAM chips for permanent data retention. Data can be stored almost indefinitely and loaded almost instantly with virtually zero chance of error. A long life (10 years) lithium battery supplies power in standby mode. In the active mode, power is taken from the ZX81. Used on its own, | Timex/Sinclair 1000 |
| DecoderJohn Oliger Co. | Fits inside the ZX80/ZX81 and remaps internal RAM to 8-9K or 9-10K. For use with external RAM pack. | Sinclair ZX80, Sinclair ZX81 |
| Delta DeviceWeymil Corporation | Non-volatile memory designed by Wilf Rigter. 32K RAM with Rigter Operating System (ROS). File-handling system in less than 600 bytes. Includes: DIRECTORY: displays all programs stored in memory by name and length in bytes. 44 entries per directory. SAVE: transfers BASIC programs, variables, and machine code to storage. Works in conjunction with the NAME/RENAME features. | Timex/Sinclair 1000 |
| Downsway 16K RAM PackDownsway Electronic Ltd | Fully cased and compatible RAM pack. | Timex/Sinclair 1000 |
| Downsway 64K MemoryDownsway Electronic Ltd |  | Timex/Sinclair 1000 |
| Econo Tech 16K RAM PackEconoTech | Budget model 16K RAM supplied without case, gold-plated contacts. Designed to prevent wobble. | Timex/Sinclair 1000 |
| FD16K RAMFuller Micro Systems | Memory expansion that fits inside the Fuller keyboard and requires the Fuller motherboard. | Timex/Sinclair 1000 |
| FD64K RAMFuller Micro Systems | Memory expansion that fits inside the Fuller keyboard and requires the Fuller motherboard. | Timex/Sinclair 1000 |
| Hardwire RAM PackIndiana Software Group Inc. | Kit and instructions to permanently connect RAM pack to computer. | Timex/Sinclair 1000 |
| Hunter 8K Nonvolatile CMOS RAM/EPROMHunter Electronics | Up to 8K RAM or EPROM; works with 16K RAM packs. Store your own system utilities or build a library of machine language routines. Can be used with any ROM or RAM. | Timex/Sinclair 1000 |
| Internal 16K RAM ExpansionIndependence Research | PC board and instructions. Instructions, $7.95. | Sinclair ZX81 |
| Jigsaw 16K RAMGladstone Electronics | Can be used with Jigsaw 32K Plus to upgrade to 48K. LED power indicator. | Timex/Sinclair 1000 |
| Jigsaw 32K RAMGladstone Electronics | 32K RAM operates in tandem with a 16K to provide up to 48K RAM. Compatible with the Data-Assette ZX99. LED power indicator. | Timex/Sinclair 1000 |
| Jigsaw 64K RAMGladstone Electronics | 64K RAM extends usable memory to 56K. LED power indicator. | Timex/Sinclair 1000 |
| LARKEN RAMdiskLARKEN Electronics | Expands the 2068 with up to 256K of nonvolatile RAM. Includes LKDOS Extended BASIC cartridge and memory board that attaches to expansion port. LKDOS uses standard BASIC commands (LOAD, CAT, SAVE, etc) to operate the RAM disk. Uses 32K (62256) CMOS RAM chips backed up with a battery; comes with 64K. Compatible with Spectrum, OS-64 | Timex/Sinclair 2068 |
| M-16 Memory ModuleByte-Back Co | Stackable with Sinclair RAM or other M-16 modules to 48K. | Sinclair ZX80, Timex/Sinclair 1000 |
| M-48 Memory ModuleByte-Back Co | 48K RAM module. | Sinclair ZX81, Timex/Sinclair 1000 |
| M-64 Memory ModuleByte-Back Co | Low power, no extra power supply required. Area from 8-16K can be switched out in 2K increments to accommodate memory-mapped peripherals, EPROMs, etc. | Timex/Sinclair 1000 |
| MEMIC-81Cambridge Microelectronics | Contains one or two 2K (6116) CMOS RAM chips. Memory is addressed into the ROM area from 8K-16K in the ZX-81 memory map. The address at which each chip appears can be adjusted to any 2K section within that area. Lithium battery in the unit provides a back-up power while the computer is switched off. | Timex/Sinclair 1000 |
| Memopak 16KMemotech | 16K RAM unit expansion capabilities through its piggy back connection and is fully compatible with Timex or Memotech 16Ks to give 32K RAM. | Timex/Sinclair 1000 |
| Memopak 32KMemotech | The 32K Memopak could be combined with a 16K RAM for 48K RAM. It was initially incompatible with the 2040 printer. | Timex/Sinclair 1000 |
| Memopak 64KMemotech |  | Timex/Sinclair 1000 |
| Memory board with I/OWisconsinc Electronics | 16K or 32K and two 8-bit LS TTL input ports and two 8-bit latching output ports. | Timex/Sinclair 1000 |
| MinimapBASICare Microsystems, Inc. | Memory mapping device to expand address space from 64K bytes to 1 megabyte. Organized into vertical 64K pages. Up to 16 pages can be supported. All memory can be dynamically defined from within a program, allowing (for example) a program in one segment to manipulate the contents of various data segments. A module in the | Timex/Sinclair 1000 |
| MX-16 16K RAMINSIGHT | Expansion plus power supply. | Timex/Sinclair 1000 |
| MX-16 RAMPM Enterprises | Expansion RAM pack. | Timex/Sinclair 1000 |
| MX-48 RAMPM Enterprises | 48K expansion memory; with power supply. | Timex/Sinclair 1000 |
| MZ512KMatthew Zenkar | 512K RAM expansion for the Sinclair QL featuring no wait-state memory and full through port. | Sinclair QL |
| QS 16K RAMQuicksilva | Cased dynamic RAM expansion. | Timex/Sinclair 1000 |
| RAM 08BASICare Microsystems, Inc. | Low cost memory expandable from 2K to 8K. Located in an address space not used by BASIC. Ideal for data or machine coded routine shared by second program. A module in the BASICare Modular Expansion System. | Timex/Sinclair 1000 |
| RAM 16BASICare Microsystems, Inc. | 16K memory module. On-board address decoding permits simultaneous use of many RAM 16 modules in conjunction with Minimap. A module in the BASICare Modular Expansion System. | Timex/Sinclair 1000 |
| RAM 64BASICare Microsystems, Inc. | Arranged in 4 blocks of 16K; all can be used under MINIMAP control. On board address decoding allows simultaneous use of many modules with MINIMAP. A module in the BASICare Modular Expansion System. | Timex/Sinclair 1000 |
| RAM Adaptor BoardFuller Micro Systems | Adapts Sinclair RAM pack to fit inside Fuller case. | Timex/Sinclair 1000 |
| RAM for TS2000Computer Add-Ons | Announced before 2068 launched. Manufacturer assumed 2068 would be identical to Spectrum. | Timex/Sinclair 2068 |
| RAMPAK 16Micro Systems Development | Flat RAM module. 16K. | Timex/Sinclair 1000 |
| RAMPORTComponedex Ltd. | Integrated expansion system. Analog, digital I/O ports and 16K RAM expansion on one card. | Timex/Sinclair 1000 |
| SCRAM BoardSilicon Mountain Computers | Improved version of Hunter board. Comes with battery-backup to make memory non-volatile. Developed with Larken Electronics to support Silicon Mountain’s WRX-16-based high-resolution software. Mapped in the 8K from 8-16K block. Can be re-mapped to 16-24K or 24-32K. Three SCRAM boards can provide 24K RAM for the ZX81 or 40K for the TS 1500. BOARD ENABLE | Timex/Sinclair 1000 |
| SCRAM-WichSilicon Mountain Computers | SCRAM board with two 8K static RAM chips, mapped to the normal 16-32K RAM region. Top 8K can be switched out in 2K blocks, allowing you to keep machine-code above RAMTOP. | Timex/Sinclair 1000 |
| SIN 16Apropos Technology | Efficient design, uses less power. Gold-plated, heavy-duty connector prevents glitches. | Timex/Sinclair 1000 |
| Strip downCommonwealth Agency, The | Prevent RAM wobble. | Timex/Sinclair 1000 |
| SUPER SIN64 64K RAMApropos Technology | 8-16K range can switch in/out. | Timex/Sinclair 1000 |
| The Incremental 1.1East London Robotics | Fits inside computer; plugs in, no soldering; up to 16K in increments of 2K. Uses 6116 static RAM. | Timex/Sinclair 1000 |
| The Lip 16K RAMSinclair Place | “The LIP” locks on to prevent the wobbles. | Timex/Sinclair 1000 |
| TS 1016 RAM packTimex Computer Corporation | Timex’s version of the Sinclair ZX81 16K RAM pack for the Timex/Sinclair 1000. This, and the Sinclair unit, were famous for “wobble,” a condition that resulted in resetting the computer and loss of memory contents. Users overcame this problem with a variety of solutions, including Velcro between the computer and RAM pack, oversized rubber bands, | Timex/Sinclair 1000 |
| TS 1016S RAM PackTimex Computer Corporation | Prototype RAM expansion module. Internal circuit board marked “TS-1032 REV A.” Has 16 AM9016EPC 16K x 1 bit RAM chips, total of 32K RAM. Date codes on all chips are 1982, the latest is the 50th week of 1982. Only one confirmed to exist. From Eric Johnson’s collection. | Timex/Sinclair 1000 |
| UM-16 16K RAM PackByte-Back Co | “Ultimate memory” RAM pack. Battery backup, reset switch, PROM/ROM socket. | Timex/Sinclair 1000 |
| UM-64 64K RAM PackByte-Back Co | 64K RAM pack with additional features. 8-16K area selectable in 2K increments. EPROM socket for 2K/4K. Battery backup (6 AA batteries) powers RAM pack and computer for up to 30 minutes. ROM-RAM transfer: copy Timex ROM into the 0-8K area of RAM, flip a switch and operate out of RAM. Switch that only resets 16-32K | Timex/Sinclair 1000 |
| ZX-PandaData-assette | Contoured case fits snugly against the rear of the computer. LED power indicator. Expandable to 32K with plug-in module that fits inside the existing case. | Timex/Sinclair 1000 |
| ZX-Panda Expansion ModuleData-assette | Plug-in module for 16K Panda, extending the memory to 32K. | Timex/Sinclair 1000 |
| ZX81 2K upgradeMicro Basics | Kit including instructions and IC socket. | Sinclair ZX81 |
| ZX81 2K Upgrade KitJ. Balogh | Double on-board memory to 2K. | Sinclair ZX81 |