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The Memotech MTX Series


     The Memotech HRX Multimedia PC


Memotech developed a high resolution graphics package based on the MTX and FDX, called the HRX which was developed for picture and image processing. The features of HRX are described in the MTX Series Technical Specification . . . .

"The basic monochrome system uses a single "colour" plane and gives 4 pages of 256x256x8 bit storage giving 256 levels of grey per pixel. The colour system used three colour planes (R, G and B) giving 224 or 16 million colours per pixel. This is more than that required for colour TV (250,000 colour shades) and the extra storage capacity can be used for picture processing."

These specifications are likely pre-production, the hardware schematics show that the analogue to digital convertors had 6, rather than 8, bit resolution, giving 218 or 256 thousand colours per pixel. This was likely done to reduce the cost of the A/D convertors and associated RAM.

The system was designed to allow direct TV or video camera input into its frame store, the HRX had a set of analogue to digital converters which worked at video speed and fast interleaved DMA storage which allowed data to be written to the system at video frame rate (88M bit/s). This allowed the system to grab video frames in real time and perform real time image enhancement and processing.

In addition to the real time processing capability, a software package running on an MTX computer could perform fast, off-line processing of pictures stored in the HRX frame memory, including, in addition to basic dot and vector line drawing capabilities, such functions as zoom, shrink, rotate, etc.

Memotech envisaged that applications for the HRX included graphics design, image enhancement, animation etc. However, whilst the system was certainly technically advanced for its time, it is unlikely that it was commercially successful.


The HRX system gets a brief mention in the The Home Computer Advanced Course article on the Memotech company :-

"Starting with an unexpanded MTX500, the user can add disk drives and the three graphics controller boards: a 96-bit processor main controller board, a 'Frame Grabber' and a three channel A/D converter. The resulting system is able to produce animations, picture composition and graphic design up to a full typesetting capacity. The system costs around 4,500."

The HRX system is also mentioned in an article about Video Processing from the November 1984 edition of Computers & Electronics Magazine.

The HRX was also reviewed by John J. Anderson, the writer for Creative Computing, who reviewed the MTX in the June 1984 issue of the magazine, complete with an HRX image capture of himself!

Despite not being able to locate this article for a long time, I have just managed to find a copy at and posted it on the Articles page.

Sandwiched between the pages of the MTX512 review, is a half page devoted to the HRX. Anderson says "There in front of me was the most incredible video frame grabber I had ever seen."......"There have been hi-res frame grabbers before, and there will be more in the future. But the Memotech hi-res image processor represents a breakthrough in performance for the price. Sure, it's pricey - about $14,000 at the current rate of exchange for the pound sterling. But capability of this quality cost three times as much before Memotech came on the scene."

Andy Key recalls that the HRX contained a high resolution graphics card (at 256x256x18bpp) and had basic image processing, such as sharpen, blur, scale, rotate, etc. and was shown at trade shows, but he is not sure any were ever sold.

Andy also has some copies of screen captures showing the three famous actresses (no Kelly though!) at the top of this page, these captures were used during system demonstrations and showed off the impressive (for the time) capabilities of the HRX at 256x256 pixels. (The images were originally TIF images, converted to JPG for this web page).



Technical Details

Almost all of the technical details of the HRX have been lost and I believed that it was highly unlikely that any detailed technical data would ever be found. However, Tony Brewer has found some design drawings amongst the paperwork that he retained from his days at Memotech and has kindly made them available, they are reproduced below.

Claus Baekkel has also found a report in a Danish computer magazine that includes a mention of the HRX as well as a small photo, from a review of the 1984 PCW show at Earls Court. The grainy photo, also shown above, indicates that the HRX boards were located in a wider chassis than the FDX/HDX, located below an HDX type chassis. The article notes that the HRX included a 20MB hard disk. The wider chassis agrees with the information about the boards supplied by Tony.

Tony's files indicate that the HRX comprised at least three main components

  • A Video Analogue to Digital Converter board, HRX-AD1

  • A Controller / Memory board, HRX-CM

  • A "Double" Memory board, HRX-MM

Updated - August 2022

I have been in contact with Simon Goodwin, who, along with his other achievements, was a prolific writer for a number of computer magazines in the 1980s. In 1984, Simon attended the PCW Computer Show at Earl's Court and shortly afterwards, was sent a copy of the "HRX Graphics System -HRG Utility Software Manual" by the Memotech sales team. Thanks to Simon's preserving of this otherwise long lost document, I can now post it here.

Section 1 of this document provides a technical description of the HRX hardware and is almost certainly the most detailed description of the HRX hardware that is in the public domain.

Video Analogue to Digital Converter board, HRX-AD1

Hand drawn schematics for the Video A/D Converter board

 - not surprisingly, the digitising circuit is very similar to my Video Wall

The file also contains a hand written parts list for the A/D board

Controller/ Memory board, HRX-CM

A copy of the layout for the Controller / Memory board

 - the layout shows 256KB of RAM using 4164 memory

 - a Fairchild TDC1016,  video speed, 10-bit D/A converter

Hand written parts list for the Controller / Memory board

Double Memory board, HRX-MM

A copy of the layout for the Double Memory board

 - the layout shows 2 banks of 256KB of RAM using 4164 memory

 - a pair of Fairchild TDC1016s,  video speed, 10-bit D/A converters

Hand written parts list for the Double Memory board

Also includes the parts list for a "Frame Grabber" board, which Tony advises is just an other name for the A/D converter board, and in fact, has the same parts listed as on the A/D board.



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Page last modified 16/08/2022