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staticmem

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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

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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..

 

static UINT8 palette[] =
{
0x00,0x00,0x00, /* black	*/
0xf0,0x00,0x00, /* red	  */
0x00,0xf0,0x00, /* green	*/
0xf0,0xf0,0x00, /* yellow   */
0x00,0x00,0xf0, /* blue	 */
0xf0,0x00,0xf0, /* magenta  */
0x00,0xf0,0xf0, /* cyan	 */
0xf0,0xf0,0xf0, /* white	*/
0x08,0x08,0x08, /* black	*/
0xe0,0x08,0x08, /* red	  */
0x08,0xe0,0x08, /* green	*/
0xe0,0xe0,0x08, /* yellow   */
0x08,0x08,0xe0, /* blue	 */
0xe0,0x08,0xe0, /* magenta  */
0x08,0xe0,0xe0, /* cyan	 */
0xe0,0xe0,0xe0, /* white	*/
0x10,0x10,0x10, /* black	*/
0xd0,0x10,0x10, /* red	  */
0x10,0xd0,0x10, /* green	*/
0xd0,0xd0,0x10, /* yellow   */
0x10,0x10,0xd0, /* blue	 */
0xd0,0x10,0xd0, /* magenta  */
0x10,0xd0,0xd0, /* cyan	 */
0xd0,0xd0,0xd0, /* white	*/
0x18,0x18,0x18, /* black	*/
0xe0,0x18,0x18, /* red	  */
0x18,0xe0,0x18, /* green	*/
0xe0,0xe0,0x18, /* yellow   */
0x18,0x18,0xe0, /* blue	 */
0xe0,0x18,0xe0, /* magenta  */
0x18,0xe0,0xe0, /* cyan	 */
0xe0,0xe0,0xe0, /* white	*/
};

static PALETTE_INIT( mbee )
{
int i;
palette_set_colors(machine, 0, palette, 32);
for( i = 0; i < 256; i++ )
{
	colortable[2*i+0] = i / 32;
	colortable[2*i+1] = i & 31;
}
}

Edited by Robert
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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

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how could I make the program available here ?

 

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.

Edited by Robert
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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

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  • 3 months later...

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. :)

Edited by z80
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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

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  • 5 months later...

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

};

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