vintage-computing Tag Posts Index

PX-41CX assembly

The PX-41CX is a replica of the classic HP-16C programmers calculator. Unlike the Swiss Micros replicas DM41L and DM41X the PX-41CX comes a kit for self assembly

PX-16C assembly

The PX16C is a replica of the classic HP-16C programmers calculator. Unlike the Swiss Micros replicas DM16 and DM16L the PX16C comes a kit for self assembly which

Casio fx-602P from 1981 - The best calculator Casio ever made?

A video on one of my favourite programmable calculators. I think keystroke programming is an underrated technique. While Basic and later Pascal style languages are

HP-16C Programmers Calculator

The HP-16C is quite a rare calculator from the HP Voyager series. It's made specifically for software developers. While most scientific calculators from the 1990

Ben Eater 6502 Kit — Day 22

The interrupt requests are meant to be shared between several advanced devices. The breadboard 65C02 computer has only one of those: The 65C22 VIA (versatile interface

Ben Eater 6502 Kit — Day 21

The 65C02 has two interrupt lines: NMI (mon maskable interrupt) and IRQ (interrupt request). It should be noted that IRQ are mend to be shared between interrupt

Ben Eater 6502 Kit — Day 20

The ordered spare parts have arrive and not a minute too late. The poor EEPROM looks pretty beaten: One leg broken off at the case Three legs broken on the opposite

Ben Eater 6502 Kit — Day 19

Up until now the computer was run either by a fairly slow 555 timer or even slower single stepping. This was possible because the WDC-65C02, unlike the R-65C02,

Ben Eater 6502 Kit — Day 18

As the programs become more complex debugging becomes more difficult at well. All you have are hex codes which you need to interpret yourself: Current Monitor output

Ben Eater 6502 Kit — Day 17

Now we have some RAM we have stack and can use subroutines to make the program more compact. I already used macros and include files so I can just rewrite the macros

Ben Eater 6502 Kit — Day 16

Ben Eater used a single SN74H00N 4×2 NAND chip as memory management unit which decoded 3 address lines (A13 … A15). This saves integrated circuits but has a few

Ben Eater 6502 Kit — Day 15

The first version of the Hello World program in bare metal 65C02 assembler was 342 bytes long. That's quite a lot for such a simple assembler program. We can certainly

Ben Eater 6502 Kit — Day 14

The computer is coming along nicely. Next a Display is added to the system. Adding power Close up The display hangs a bit over the side of the board as the SN74LS21

Ben Eater 6502 Kit — Day 13

Up until now programming was done in hex code. Which is quite cumbersome and error prone. It's time to switch to more powerful tools. But first I have to repair

Ben Eater 6502 Kit — Day 12

In order for something happen a computer need some kind input and output. For 65C02 the best choice of I/O is the 65C22 VIA (Versatile-Interface-Adapter). It offers

Ben Eater 6502 Kit — Day 11

Up until now the 65C02 was only supplied with NOP operation. Including the reset and interrupt vectors making the CPU start execution at EAEA₁₆ while the first address

Ben Eater 6502 Kit — Day 10

After I checked the CPU by hardcoding a NOP operation with 8 1kΩ resistors the next step is adding a ROM to for the future programs. Or better an EEPROM (electrical

Ben Eater 6502 Kit — Day 9

Good news. The CPU wasn't damaged after all. The RES (Reset) pin was bent inwards. To bad I didn't make a photo to show how that looked like. Anyway, with the RES

Ben Eater 6502 Kit — Day 8

It seems that the broken power supply has also destroyed the CPU itself. That's very bad and I have to order new one. Getting hold of a WDC60C02 (WDC = Western Design

Ben Eater 6502 Kit — Day 7

One of the advantages of the WDC60C02 is the fully static design. This makes it possible to stop the CPU clock at any time without the CPU loosing its status. You