Hp45 microcode
#1

Whoever has problems squeezing the microcode instructions in the rom of a ucontroller, can try the following to save space:
There are 1024 possible instructions, but only about 526 are used.
The Roms 1,5 and 6 use a similar subset of only 254 instructions. So you number the 254 instructions from 0 to 253 and store them instead of the original 10bit instructions. Next you have to build a translation table which translates the 8 bit number to the original opcode.

If you only have the choice between 8 and 16 bit words, you can save space:

before: 8Roms*256Instructions*16Bit

after: 5ROMS*256Instructions*16Bit+
3ROMS*256Instructions*8Bit+
1Translation*254Instructions*16Bit



Possibly Related Threads…
Thread Author Replies Views Last Post
  HP45/32E Connection Matt Agajanian 2 1,376 07-07-2012, 06:31 PM
Last Post: Matt Agajanian
  HP45 Battery Pack Disassembly Eric_G 4 1,528 05-11-2011, 11:42 PM
Last Post: Eric_G
  HP-35 Microcode-level Emulator (in JavaScript!) Ashley Nathan Feniello 4 1,428 10-02-2010, 03:23 PM
Last Post: Frank Boehm (Germany)
  HP-35 Microcode-level Emulator (in JavaScript!) Ashley Nathan Feniello 1 944 09-02-2010, 01:39 AM
Last Post: Pal G.
  HP45 - internal pics Alberto Fenini 2 1,168 08-17-2010, 04:27 PM
Last Post: Alberto Fenini
  HP45 Original Price Bon 12 2,945 04-08-2010, 04:14 PM
Last Post: Wingman54
  Capricorn CPU microcode Olivier De Smet 6 1,946 03-10-2010, 03:50 AM
Last Post: Olivier De Smet
  HOT HP45 sale at ... you know where Alan Firth 4 1,436 01-20-2007, 12:26 PM
Last Post: David Smith
  How to halt green corrosion on HP45 copper battery contacts in battery bay? JaSon 1 1,040 07-01-2006, 07:27 AM
Last Post: David Smith
  HP35 HP45 battery charger. Random display values. Charles Esson 3 1,210 10-26-2005, 10:13 AM
Last Post: Thomas Radtke

Forum Jump: