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HP-71B MultiMod ROM Emulator User Manual
01-18-2021, 04:39 AM (This post was last modified: 01-18-2021 08:30 PM by Sylvain Cote.)
Post: #3
RE: HP-71B MultiMod ROM Emulator User Manual

I did a first pass reading and I have not completely double checked with the Hardware IDS but if you follow the H-IDS, then there is an error at page 6:

this line
   -------[ROM ID code]--------  Flag  Addr  Chip ; Comment
DB 0x0a, 0x00, 0x01, 0x00, 0x08, 0x00, 0x20,    1 ; 16K forth
//  32K  resv   ROM   n/d  Last  Not-last

should be
   -------[ROM ID code]--------  Flag  Addr  Chip ; Comment
DB 0x0b, 0x00, 0x01, 0x00, 0x08, 0x01, 0x20,    1 ; 16K forth
//  16K  resv   ROM   n/d  Last  Last

There are other errors in the example, if I have understood correctly of course.

From what I can deduce, the only reason the Flag field exist is because you need a way to specify the hard-coded ROM, otherwise the [Nibble 4 : Last Chip] field should be enough.


5-nibble ID code as described in Hardware IDS

Nibble 0 : Address Space Size
Value     Memory Size
-----  ----------------
  F        1K      512
  E        2K       1K
  D        4K       2K
  C        8K       4K
  B       16K       8K
  A       32K      16K
  9       64K      32K
  8      128K      64K
  7      256K     128K
-----  -------  -------
Value  Nibbles   Bytes
n/s = not specified

Nibble 1 : Reserved

Nibble 2 : Device Type
   0 : RAM
   1 : ROM
2..E : Assorted Memory Types
   F : Memory Mapped I/O

Nibble 3 : Device Class
Memory : 0..F : Unassigned
MM I/O :    0 : HP-IL Mailbox
MM I/O : 1..F : Unassigned

Nibble 4 : Last Chip
bit 3 : Last chip in module
bit 2 : Last chip in sequence
bit 1 : Unassigned
bit 0 : Unassigned

Edit: rework Address Space Size table to add byte sizes
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RE: HP-71B MultiMod ROM Emulator User Manual - Sylvain Cote - 01-18-2021 04:39 AM

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