New Version of OS/X Scelbi Emulator Posted
Here is a summary of some of the main changes:
Mark Arnold (one of the original authors of SCELBAL) has fixed some mistakes in the version of SCELBAL I was originally using. These mistakes were introduced during the reconstruction of the program.
I have made changes to AS8 to support the RST instruction and my interpretation of how OUT port numbering should be implemented. If you are interested in this version, drop me an email.
The SCELBI expects that all inputted characters have the high bit set – and starshooter and SCELBAL have been reassembled to match. The power function such as 2^3 did not work in SCELBAL prior to this change.
The emulator itself now accurately counts cycles based on information gleaned from the 8008 data sheet. Each cycle takes 2 clocks and instructions take from 3 to 11 cycles. The emulator executes 250,000 cycles per second, same as an actual 8008. I should do some measurements using SCELBAL, but I’ve guessed that an 8008 might execute something like 30,000 instructions per second while running a typical program.
This version of the emulator uses port numbers to select serial or byte I/O, so the byte I/O menu has been removed. This effectively emulates a SCELBI with both serial and parallel (BYTE I/O) ports connected.
My 8008/SCELBI webpage can be found at this link-