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Back in the 1980's amongst other things I made commercial laser printers that emulated line, dot matrix, daisy wheel printers and other laser printers. Initially memory was very expensive and limited thus lines were compiled and sent to the laser printing engine on the fly. When memory became...

10Base2 is designed for 50 ohm characteristic impedance. It's rather tolerant but you may encounter signal problems such as unwanted signal artefacts if using 75 ohm characteristic impedance. Only ground one of the terminators NOT BOTH! The best way to test your installation is with a TDR (Time...

If you're testing with %FF's it's best to weakly pull up the data lines via resistors to VHigh to prevent the bits from changing. Likewise for NOP %00 testing but pull down to ground. The last thing one wants to do is tie the data lines directly to GND or VCC.

A funny soldering job on the adapter card. The SMD components seem to have far too much solder on them. One can replace the square pins with appropriate round pins from companies like mill-max.

Replace DJNZ with DCR B JNZ LOOPB

Not bad. Partial signs of life!

The Aussie Hi-Tech C!

Here's an interesting blurbette from ASIX "In order to be compatible with some legacy software, some users might need to remap the assigned I/O addresses of AX99100 Parallel/Serial ports to Legacy (ISA type) I/O address (such as 378h, 3F8h, etc.). It is possible on DOS and Windows 95/98/ME...

Great to know! Now for a PCI-E based one.

The NSC800 has got quite a few other enhancements that make it incompatible with some undocumented instructions and existing Z80 features. e.g. 8 bit autoincrementing refresh (R) register, multiplexed data/lower address bus.

Do it the old fashioned way: make a cast plug from the broken piece, infill the missing bits and make a new one out a material that can handle the torque.

Someone suggests that you contact Analog Devices because they now own Linear Technology.

Note the@9's only appear if the CPU is executing repeated RST 38Hs (op code FFH).

The ladder has mazes comprising of 79 columns and 20 rows. How is this going to work on a TRS80 with 64 columns and 16 rows?

The AM radio and other spurious emissions from home computers caused TVI and other safety issues which forced the appropriate FCC and worldwide equivalent regulations to be formulated. Welcome to the world of EMC (electromagnetic compliance)!

Self modifying code isn't the only hurdle. There are many sneaky techniques to minimise the program size and maximise the performance of Z80/8080 programs. When someone used self modifying code from ROM a template is kept in ROM then copied to RAM during initialisation with the RAM copy being...

There's a high chance that it'll be something simple! Percussive maintenance seems to work and if that fails: Someone would use their EPROM EMULATOR and load it with very short and simple test routines. e.g. 18 FE or even C3 00 00 to start which will put the processor in a forever loop, then...

Accessing the parallel ports depends on the application. Some applications can access parallel ports at any address whereas some need the ports to be at 0x3BC, 0x378 or 0x278. Most PCI, PCI-E bus parallel adapters can't assign parallel ports to 0x3BC, 0x378 or 0x278 but some more expensive ones...

You're on the right track. Simply, just hammer the port with variable width pulses. (PWM) at an acceptable sample rate. At first when learning just play with fixed 50% duty cycle square waves of different frequencies. Start with about 200Hz and work up to 2000Hz. Once you're comfortable with...

Gee that’s keen! If you’re lucky the PAL’s verify fuse hasn’t been blown so one can read the fuse map and copy it to another PAL easily from a PAL/PLD/Universal programmer. Otherwise someone’d look at the schematic diagram and work out the expected logic and use ABEL, PALASM or CUPL. Good Luck!