The Final Traitorous Act

by Bert Martin

Bert Martin admits having become a PC proselyte, converting his Nascom as well.

The Jonahs said that it would be too slow, but it had to be done, simply to prove that it was possible. The similarities between the Z80 and 8088 chips were too tempting to ignore, while the poor old machine had almost ceased to deserve any extended use, except that it had within it virtually all of the computational support for my Ph.D. in Ikonics. (For those who need to know, Ikonics is the multi-disciplinary study of how we perceive imagery, and therefore the key to how such imagery can be re-imposed upon the mind by the transmission or recording of two-channel ‘information’.)

Having extended the machine to a single disk-drive CP/M machine, with the addition of 1Mbyte of memory (I couldn’t afford the other Mbyte at the time), bandying words with my fellow readers led me to want the PC-conversion more than I wanted to retain NASCOM/​Gemini compatibility. Not being very good at machine-code (or any other form of language, for that matter, except swearing), it became necessary to carve large slices out of existing software, then tailor the patches into a working whole.

All sixteen 64K-blocks were therefore reorganised into one block which was devoted to the boot-up sequence, additional registers, 8088-like address segmentation and a table of redirectional ‘hooks’ to the essential functionality of MS-DOS, with the other fifteen blocks emulating the remainder of the PC-XT’s standard layout, including even LIM/​EMS emulation, just in case I should ever need that other Mbyte. It wasn’t a true MS-DOS, but a rather inglorious ‘hammer and nails’ solution, which remains far too inelegant to want to demonstrate to anyone – but it works!

At a Norton rating of 0.9, it was rather slow compared to the subsequently acquired Amstrad PC1640 SD/ECD, as well as rather inconvenient, in possessing only one disk-drive compared with the latter’s 3.5″ and 5.25″ floppies, and a 21Mbyte WD ‘Filecard’. In the end it didn’t last but was pensioned off to a local software house, as a disk-formatting and copying machine – a role which may take it several years into the future.