The 'test pattern' of the Motorola MCM6830L7 ROM

[per]

I recently got myself a MEK6800D1 I decided to get back up to working condition. After doing some research, I figured that the MIKBUG and MINIBUG portions of the ROM are well documented, but the Engineering Note 100 only lables the last 256 bytes of the ROM "Pattern Data", without ever mentioning it again.

The first challenge was to dump it, since the MCM6830 uses a pinout that predates the intel-style ROMs. At first I tried to read it out over serial, using MIKBUG. I later found out that A9 is permanently tied low, so this only gave me two copies of the MIKBUG portion of the ROM. The next thing I decided to try, was to use a patch-cable based ROM-adapter board with a programmer, and by using this I was able to read out the whole 1KB on the chip.

So what was this mysterious "pattern data"?... Well... I feel like there's a story behind this somewhere, but it turns out to to be what seems like an earlier version of MINIBUG assembled to start at $EE00 instead of $FE00. Why Motorola decided to use this as a filler, I have no idea, but I'd love to know if any of you have more info on how this came to be.

Right now I'm working out reconstructing an assembly listing of both versions, then I'll use git to get a diff. There are a few small differences on how and where some of the registers of the MC6850 are handled, but nothing major.

 

[sdc695]

I recently got myself a MEK6800D1 I decided to get back up to working condition. After doing some research, I figured that the MIKBUG and MINIBUG portions of the ROM are well documented, but the Engineering Note 100 only lables the last 256 bytes of the ROM "Pattern Data", without ever mentioning it again.

The first challenge was to dump it, since the MCM6830 uses a pinout that predates the intel-style ROMs. At first I tried to read it out over serial, using MIKBUG. I later found out that A9 is permanently tied low, so this only gave me two copies of the MIKBUG portion of the ROM. The next thing I decided to try, was to use a patch-cable based ROM-adapter board with a programmer, and by using this I was able to read out the whole 1KB on the chip.

So what was this mysterious "pattern data"?... Well... I feel like there's a story behind this somewhere, but it turns out to to be what seems like an earlier version of MINIBUG assembled to start at $EE00 instead of $FE00. Why Motorola decided to use this as a filler, I have no idea, but I'd love to know if any of you have more info on how this came to be.

Right now I'm working out reconstructing an assembly listing of both versions, then I'll use git to get a diff. There are a few small differences on how and where some of the registers of the MC6850 are handled, but nothing major.

Is it possible to post or get a pointer to the "test pattern" part of the ROM. Due to the fact that it is only 256 bytes indicate that it could be posted here.

Back in the day, I made up a debugger ROM (we called it MADIC) that used an ACIA and had more commands than Mikbug. It was as Mikbug,only 512 bytes. Used every bit of it!

 

[per]

Is it possible to post or get a pointer to the "test pattern" part of the ROM. Due to the fact that it is only 256 bytes indicate that it could be posted here.

Back in the day, I made up a debugger ROM (we called it MADIC) that used an ACIA and had more commands than Mikbug. It was as Mikbug,only 512 bytes. Used every bit of it!

I'll try to dig it up from my digital archives, but as mentioned it turned out to be extremely similar to the MINIBUG module. If I remember correctly, the only significant differences are the starting address its assembled for and the IO port used for the communication interface.