After my PC-1500 memory module which need some corrections, i’m very proud to present you this incredible 512KB memory module for the PC-1600 built by Tom.
The best thing to do is to let Tom explain it :
At the beginning of 2014 I rediscovered the fascination of the vintage SHARP pocket computers. My very first computer was indeed a PC-1500/CE-150 which I found somewhere deep down in my storage. And it was still working (except the rechargeable battery of course)!
In the 80s, when I was a boy, however the PC-1600/CE-1600P was a dream, but too expensive for me by magnitudes. So I was lucky to buy one from ebay. Since I’m a computer scientist, I was interested to treat that machine like an embedded system using a modern software dev environment and the sdcc/Z80 C-compiler. I succeeded, but soon noticed that the RAM-disk was too small, even on a 32KB+64KB config.
So I searched for custom vintage Tramsoft and Bajic 256KB modules, but couldn’t get one.
That was the point, when I decided to build my own. Luckily I found the homepage of Kai Bader, who kindly offered me one of his breakout boards and I started experimenting with SRAM ICs.
The hard part for me was to decode the PC-1600 vertical bank switch of slot 2, but finally I got my first 256KB RAM module in my hands.
Technical Data (rev 1 – sold out)
* 256KB RAM module with low power SRAM chip
* 32KB can optionally be reserved as a main memory extension, the rest is used as RAM-disk
* No battery buffer
I send one to Kai and he posted it on his website. Allmost immediately I was contacted by Eric – the owner of this great site – who had some clever suggestions for technical improvements and organized a poll at the silicium.org enthusiasts forum for a revision 2 of the board.
Since my first version had a 512KB SRAM chip on board of which “only” 256KB was used, the main improvement was to provide a 2x256KB mode and a 512KB mode.
It was clear soon that the 512KB harware mode was not supported by the PC-1600 INIT-command, but after some fiddling about I managed to write a patch routine that overcomes this problem.
And that was the birth of the first 512KB RAM module for the SHARP PC-1600.
Technical Data (rev 2 – sold out)
* as rev 1 but 3 modes of operation:
– 256KB mode, without need of any additional init software or peeks/pokes
– 2x256KB mode, with two banks 256KB each – to be switched by an additional hardware switch
– 512KB mode, needs an additional custom patch routine to get that mode running
* Battery buffer not included, but a description for mod available.
For more details see
Technical Data (rev 3 – planned)
* as rev 2 but with (better) battery buffer support incorporated
Thanx again Eric for your support and this very informative and entertaining site.
Thank you Tom for this module !
My friends from Silicium and me are happy with our 512KB PC-1600 🙂