[The Spectrum ROMs Collection]

Philip Kendall - Suffolk Science ROM

From James Smith:

"I've been "e-bay"-ing recently and in a purchase of broken machines I came across this hardware device. It looks like a Disciple interface and has a 25-pin D socket at the back. When I plug it in it takes over the ROM and identifies itself as a "Suffolk science" device. It appears to have been used in schools and can do analogue + digital measurements amongst other things. One was on sale on Ebay recently and went for £40 - and I have two of these devices :-)

I don't know how this device works, except that it responds to OUT 127,1 to page it in. The ROM seems to contain BASIC programs too. Inside the device there are 4 EPROMs, but I can only page one of them in. Doing an OUT 127,45 seems to page both ROMs out. Doing an OUT 127,7 returns the ZX ROM into the memory map."

And more information from James:

"I have been doing some more research, and I was still uncomfortable that there were 4 EPROMs inside the unit, yet I was only getting one ROM image that made sense. I therefore went for the "ultimate" test, and took my unit apart. I put each EPROM into my trust BBC computer and dumped each ROM to disc with a little machine code program - nice to know the 6502 skills are still with me :-)

The four EPROMs are colour coded and go red,yellow,green and blue. The PCB of the unit is marked (c) 1989 to Suffolk LEA. The PCB is marked v3.0. There are not many chips on the PCB, apart from the 4 EPROMs the rest are just TTL logic chips. I think the BASIC programs inside the ROM will give clues on how to read the A/D ports.

The ROM is complex, because when it powers up it copies some of itself into RAM (just below &7FFF) and runs from there. It also sets up a paging routine and keeps track of itself in a similar way to the 128 BANKM mechanism."

Please get in contact if you have any more details on this device.

Valid XHTML 1.0! Valid CSS!