---
title: "4K High Resolution Graphics ROM"
id: 11620
type: "product"
slug: "4k-graphics-rom"
url: "http://localhost/product/4k-graphics-rom/"
markdown_url: "http://localhost/product/4k-graphics-rom.md"
published_at: "2019-11-30T01:22:36+00:00"
modified_at: "2026-03-22T13:20:11+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2019/11/4K-Graphic-ROM-Gladstone-catalog-Feb-1983_0002.jpg"
excerpt: "Gives 448 extra pre-programmed graphics symbols. The ROM contains lower-case letters, bombs, bullets, rockets, tanks, a complete set of invaders graphics and more. The board also has a spare socket that will accept another 4K of ROM, like the 4K TOOLKIT ROM or 1K/2K RAM, for user-defined graphics. dk'Tronics and Kayde published several games that…"
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company:
  id: 10819
  title: "DK’tronics"
  type: "company"
  url: "http://localhost/company/dktronics/"
price: 53.91
date: 1982
rarity: "Uncommon"
producturl: "http://www.zx81stuff.org.uk/zx81/hardware/4KRom"
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        title: "SYNC v2 n5"
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---

# 4K High Resolution Graphics ROM

Gives 448 extra pre-programmed graphics symbols. The ROM contains lower-case letters, bombs, bullets, rockets, tanks, a complete set of invaders graphics and more.

The board also has a spare socket that will accept another 4K of ROM, like the [4K TOOLKIT ROM](http://localhost/product/4k-toolkit-2/) or 1K/2K RAM, for user-defined graphics.

[dk’Tronics](http://localhost/company/dktronics/) and [Kayde](http://localhost/company/kayde-electronic-systems-ltd/) published several games that required this ROM:

- [Asteroids (dk’Tronics)](http://localhost/product/asteroids-2/)
- [Centipede (Kayde)](http://localhost/product/centipede-2/)
- [Defender (dk’Tronics)](http://localhost/product/defender/)
- [Peckman (Kayde)](http://localhost/product/peckman/)
- [Space Invaders (Kayde)](http://localhost/product/space-invaders-4/)

![Image](http://localhost/wp-content/uploads/2020/08/4k-graphic-ROM-Sync_V2_N5_p94-300x267.jpg)

### Technical

The 4K EPROM is mapped to 2000h-2FFFh, with seven new character sets (of 64 symbols each). 2E00h-2FFFh is mainly filled with FFh and contains a few USR functions for selecting the new character sets. The board can be fitted with 1K or 2K static RAM, or 4K EPROM (mapped to 3000h-3xFFh).

Only 64 symbols can be used at once, preventing display of lower-case letters and numeric digits. Many symbols (like A-Z) are duplicated in several 64-character banks, which is why it claims 448 extra symbols (vs the 512 that could be available).

### Kayde 4K ROM

Kayde’s variant is a possibly unlicensed clone of the dk’tronics board. With the exception of a few cosmetic differences to the circuit and replacement of some inverse characters with Pac-Man symbols, it is otherwise identical.