More HP microcode & loader rom detective work

From: Bob Shannon <>
Date: Sun Aug 1 07:38:59 2004

Most often I build small 'emulators' that use a microcontroller and an

Using a PC parallel port should work just fine. You need to monitor the
COMMAND flag from the I/O board.

At power up, or following a PRESET operation, DEVICE COMMAND will be
asserted, and the PC or emulator should pre-clock the interface DEVICE FLAG
input to clear this 'false' request.

Once pre-clocked, eash assertion of DEVICE COMMAND should be followed
by sending the 8-bit parallel data, then strobing DEVICE FLAG. A
correct load will
halt with 102077 in the S-register.

If your directly connecting the PC to the HP, be careful about ground
loops and
latchup issues if both devices are not powered up at the same moment.
 If you need
to power the emulator up seperately from the HP I'd reccomend some form of

Dwight K. Elvey wrote:

>>From: "Bob Shannon" <>
>>Jay West wrote:
>>>1816-0420 No clue
>>Paper tape. This is the 'fastest' easy way to bootstrap an HP 1000.
>>Use this with a 12566 microcircuit I/O board, and you can load a 31K word
>>boot image in less than 2 seconds, faster than many stock HP disk drives.
> What data source are you using? I was thinking of connecting
>this board to the parallel port of my PC to make the PC look like
>an external drive.
>>Use this boot rom with the emulator I'm building for you. I'll supply a
>>cable and jumper settings for the I/O card (gnd true).
Received on Sun Aug 01 2004 - 07:38:59 BST

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