Hi all,

I'm seeking some information concerning a small PROM IC used in the early Microbee colour board circuit MB1217. The part is IC 7 an 82S123 PROM. This IC is used to determine the foreground RGB and intensity levels given an input value.

Essentially the information I am after is to know what output values will be on IC 7 pins 1-6 with each input combination applied to pins 10-14 (32 combinations).

Cheers
staticmem

I know which rom you mean, it is on the video board with the 6545 CRTC etc.

But...

Seems that rom/pal isn't used in MESS, otherwise I would have listed the hex dump for you.

The contents aren't listed in the service manual either.

But... found this listing in the MESS microbee driver, maybe it will help..

Robert, thanks for your updated post, going by what I have seen in an early Microbee technical manual and running MESS the colour scheme in MESS looks incorrect.

A fairly detailed study of the colour board schematic reveals 64 colour combinations but only 26 of these are unique colours, all the possible colours can be worked out for the background. The 82S123 is used to determine what colour is used for the foreground with the input to it converted to 1 of 32 different colours, but again only 26 of these are unique colours but in a different arrangement to that used for the background.

I have written a small Microbee program that displays the 32 foreground colour combinations, if I can't obtain the 82S123 data then the next best thing is for someone to run this program on an old colour disk or tape model (i.e. not a Premium) and take a picture and post it back. I can then put this into "The Gimp" and hopefully create a table of data from that.

If any is able to help out how could I make the program available here ?

Cheers
staticmem

You don't have enough posts to be able to attach files, so PM me when you're ready.


EDIT: Here is the program to display colours on a microbee or a suitable emulator such as uBee512 or RMESS.

Robert has edited his previous post to include an attachment to the colour test program, so if you have a real Microbee that is an old colour model (pre Premium) ROM or disk, then run the program and take a picture and post it or send to the author of the uBee512 emulator project. The address is ubee512 AT gmail.com

Cheers
Stewart

If the 82s123 is located near the CRT controller, then about 20 years ago I actually had to program one up to hand build my first microbee from a schematic diagram.

It is a fusible link prom that gets programmed one bit at a time.

This is the data:-

65 92 55 91 96 92 95 91 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1 d5 d1

It is a critical component and is essentially used as a complex gate array.


hope that helps.

Thanks, but I think that's the PROM used to select VDU RAM for access by the CPU and 6545. It's located on the main board (IC16). The one I am after will be located on the early colour board circuit which I believe was a separate board mounted under the main board.

Stewart

Thanks z80 for that info. I've made a small file (= a rom) with that, for use with the MESS project. Now, all we need is that elusive colour prom...

The PROM values are now known. For those interested:

http://microbee.no-ip.com/beeboard/viewtop...hp?p=6242#p6242

Ah, thank you sir.
Sorry my Basic skills weren't up to scratch..

I don't think there is any issue with your Basic skills, the Microworld Basic is just slow for this type of thing.

Anyway here's the data:

//==============================================================================
// 82S123 PROM Colour table used on colour board (IC 7).
//
// The values found here have been reversed engineered by running some capture
// software on a standard colour model reading the values back in on the
// Microbee's parallel port. The software took multiple samples to eliminate
// sync signals from the final result.
//
// See Microbee Disk System manaul section E-9.
//
// There are 26 unique colour combinations, or 27 if black is counted.
//
// Colours names with a leading '#' are colours that are not easy to describe
// and the colour description is intended as a guide only.
//==============================================================================
uint8_t ic_82s23[32] =
{
// nn Colour
0x00, // 00 black
0x09, // 01 blue
0x12, // 02 green
0x1b, // 03 cyan
0x24, // 04 red
0x2d, // 05 magenta
0x36, // 06 yellow
0x3f, // 07 white

0x0b, // 08 #dark cyan
0x13, // 09 #aqua
0x0d, // 10 #purple
0x2d, // 11 #pink
0x16, // 12 #green
0x26, // 13 #orange
0x07, // 14 #grey
0x3f, // 15 #white

0x00, // 16 black
0x01, // 17 blue II
0x02, // 18 green II
0x03, // 19 cyan II
0x04, // 20 red II
0x05, // 21 magenta II
0x06, // 22 yellow II
0x07, // 23 white II

0x0f, // 24 #blue
0x17, // 25 #green
0x1f, // 26 #cyan
0x27, // 27 #pink
0x2f, // 28 #pink
0x37, // 29 #beige
0x07, // 30 #grey
0x3f // 31 #white
};

I've typed it into a new rom, and added it to MESS.
But haven't got around to hooking it up to the code yet.