---
title: "The Lambda PC8300"
id: "25826"
type: "post"
slug: "the-lambda-pc8300"
published_at: "2020-07-03T19:48:12+00:00"
modified_at: "2023-01-18T17:32:59+00:00"
url: "http://localhost/blog/the-lambda-pc8300/"
markdown_url: "http://localhost/blog/the-lambda-pc8300.md"
excerpt: "The PC8300 was announced at the 1983 Consumer Electronics Show. Marketed, and maybe manufactured, by Unisonic, it was a “clone” of the ZX81. The ROM featured a highly similar BASIC but with the character code table moved to the custom..."
taxonomy_category:
  - "Blog"
taxonomy_post_tag:
  - "Lambda 8300"
  - "Silicon Mountain Computers"
taxonomy_indiv:
  - "Fred Nachbaur"
---

The [PC8300](/computers/lambda-8300/)
 was announced at the 1983 Consumer Electronics Show. [Marketed, and maybe manufactured, by Unisonic](https://archive.org/details/creative_computing_apr83/page/n41/mode/2up)
, it was a “clone” of the ZX81. The ROM featured a highly similar BASIC but with the character code table moved to the custom chip.

As a clone, it wasn’t particularly compatible with the ZX81:

- the display file appears before the BASIC program on the PC8300
- it’ll load programs but not the variables
- ROM routines are “scrambled,” preventing one from using ROM calls in machine language
- programs with embedded machine language won’t run because they load at a higher place in memory
- the hardware of the display system is sufficiently wonky to preclude simply using a Sinclair or Timex ROM

On the hardware side, it was very compatible: most T/S peripherals could simply attach and work.

A few years after its announcement, the PC8300 showed up in surplus dealer ads, [like this one in Byte, for $30](https://archive.org/details/eu_BYTE-1988-07_OCR?q=pc8300)
.

Fred Nachbaur [developed a ROM](/product/pc8300-timex-rom/)
 that offered greater compatibility with the T/S computers. It was a simple, drop-in replacement that offered “90% compatibility.”

### Tags

[Blog](/category/blog/)
[Lambda 8300](/tag/pc8300/)
[Silicon Mountain Computers](/tag/silicon-mountain-computers/)

### People

[Fred Nachbaur](/indiv/fred-nachbaur/)

### About The Author

[David Anderson](/author/david/)
I'm a big fan of the Timex/Sinclair computers: my first was the TS 1000. I love building things for my TS 2068 and sharing them with others on this site and andertone.com.