High Speed Serial Port for the Apple II PCPI Applicard

The PCPI Applicard is one of the best CP/M cards ever made for the Apple II. It contains a Z80 chip running at either 4 MHz or 6 MHz, has it’s own 64K of RAM, and supports and optional CTC timer chip. It’s one drawback is that I/O is handled through the the Apple II and this severely restricts serial port performance.  While I can obtain 115k baud rates in native Apple II mode with ADTPro and my Super Serial card, you’re limited to around 2400 baud when I attempt serial transactions through the Applicard.

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Kaypro 4-84 Restoration

Fun with the Kaypro 4

Kaypro 4-84

I had never really planned on owning a Kaypro 4, but one day I came across a poor neglected little CP/M machine and I just couldn’t let it be taken to the dump. So I decided to take it home and see what I could do with it.

The Kaypro-4-84 is a nice little machine. It has a 4 MHz Z80 processor and a Z80 SIO chip with CTC for serial interfacing (similar to my Apple II PCPI Applicard with the Klein-Baker SIO card attachment). It’s also fairly portable, has a nice sharp monitor display, and who can resist that sleak smoky gray exterior.

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Senior PROM Reverse Engineering for the Apple IIe

seniorp1

Background

The Senior PROM was a remarkably simple and beautiful debugging/cracking product for the Apple II. Other similar products were the Wildcard and the Crackshot, however, these two products both took up a slot in the Apple II and were also detectable by certain games. Choplifter was one game rumored not to run with a Wildcard installed and it also checked the ROM contents looking for non-factory ROM loads before it launched the game. I remember there being a number of complaints around Choplifter when the Apple IIc was released because the IIc had a newer ROM not recognized by game.

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Apple IIe ROM Hacking

apple ii rom krack

Background

Many years ago I read a great article in Computist Magazine about modifying the Apple ][+ ROM code to allow halting the computer at any point in time for debugging/cracking purposes, something I had always wanted to do as a teenager. The older Apple IIs had monitor ROMs that effectively allowed you to break into the monitor at any point in time, giving you the familiar monitor asterisk prompt. Later Apple II’s that followed, however, used different ROMs that removed this feature. Even having the ability to break into the monitor didn’t always give the user full access to the loaded code. Clever programmers would put parts of their program in the screen memory locations so breaking into the monitor prompt would then wipe key portions of the code.

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