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Same thought I have. 15 years of SysAdmin and wanting to move on to something else. What boggles my mind in this video as example. Do the DOS drivers as an exam

Same thought I have. 15 years of SysAdmin and wanting to move on to something else. What boggles my mind in this video as example. Do the DOS drivers as an example actually communicate with the chips on the PCB, or are there firmware/data burnt on to the chips? I'm confused in that what it looks like is all you need to do is design a schematic and place chips down on to a PCB and then write software drivers. I thought chips had to be coded too.

_Microft 4y ago
The card for the CD drive actually uses only stock logic chips but no microcontrollers at all and therefore need no ROM dump of an existing card to work. You can find the list on the Github page of the project: https://github.com/AkBKukU/CM153-Repro https://github.com/AkBKukU/CM153-Repro
xani_ 4y ago
ISA bus is basically just quasi-memory bus with some extras. You get address, you either get data or send data, done. You just set an address and write/read data to it. All you need to do simple input/output on it is to * wait for "right" address on bus and "right" pins to light up * either latch the data, or output the data * bang the right control bit. It is entirely doable using basic logic chips, because back then any kind of programmable logic was super expensive. Compare it to usb-c where you need tens of thousands of lines of code to even negotiate some power stuff (or use specialized chips... that have those tens of thousands of lines of code baked in).
mmastrac 4y ago
In this case it is effectively a fancy serial port, which means all the chips do all the work for you, no programming needed.
tenebrisalietum 4y ago
The ISA bus is basically connected directly to the CPU. See its pinout - site is in German but there is a nice diagram. https://de-academic.com/dic.nsf/dewiki/643647 https://de-academic.com/dic.nsf/dewiki/643647 The lines marked Addr are address lines, and Data are data lines. Things that appear readable/writeable to the CPU as RAM manipulate the MEMW/MEMR lines, and things that appear readable/writeable to the CPU using its "I/O port" instructions manipulate the IOW/IOR lines. I don't know the low level protocols used there but there is definitely one and why some simple logic chips had to often be added I guess (74SNxxxxx chips very common). RAM basically does the same thing, as well as anything built in like the clock chip, keyboard controller, serial ports, floppy controller, etc. One big disadvantage of ISA is that the bus when it was introduced had to run at the same speed as the CPU. When CPUs started getting faster than 8Mhz something was done to keep the ISA bus as 8Mhz, but not sure what. The other big disadvantage is that this was intimately tied to the 8088 Intel CPU signal lines. PCI (and other things like NuBus and MCA) were CPU independent and required a chipset or other controller to interface, and that's where the complexity started to take off.

_Microft 4y ago

The card for the CD drive actually uses only stock logic chips but no microcontrollers at all and therefore need no ROM dump of an existing card to work. You can find the list on the Github page of the project: https://github.com/AkBKukU/CM153-Repro https://github.com/AkBKukU/CM153-Repro

xani_ 4y ago

ISA bus is basically just quasi-memory bus with some extras. You get address, you either get data or send data, done. You just set an address and write/read data to it. All you need to do simple input/output on it is to * wait for "right" address on bus and "right" pins to light up * either latch the data, or output the data * bang the right control bit. It is entirely doable using basic logic chips, because back then any kind of programmable logic was super expensive. Compare it to usb-c where you need tens of thousands of lines of code to even negotiate some power stuff (or use specialized chips... that have those tens of thousands of lines of code baked in).

mmastrac 4y ago

In this case it is effectively a fancy serial port, which means all the chips do all the work for you, no programming needed.

tenebrisalietum 4y ago

The ISA bus is basically connected directly to the CPU. See its pinout - site is in German but there is a nice diagram. https://de-academic.com/dic.nsf/dewiki/643647 https://de-academic.com/dic.nsf/dewiki/643647 The lines marked Addr are address lines, and Data are data lines. Things that appear readable/writeable to the CPU as RAM manipulate the MEMW/MEMR lines, and things that appear readable/writeable to the CPU using its "I/O port" instructions manipulate the IOW/IOR lines. I don't know the low level protocols used there but there is definitely one and why some simple logic chips had to often be added I guess (74SNxxxxx chips very common). RAM basically does the same thing, as well as anything built in like the clock chip, keyboard controller, serial ports, floppy controller, etc. One big disadvantage of ISA is that the bus when it was introduced had to run at the same speed as the CPU. When CPUs started getting faster than 8Mhz something was done to keep the ISA bus as 8Mhz, but not sure what. The other big disadvantage is that this was intimately tied to the 8088 Intel CPU signal lines. PCI (and other things like NuBus and MCA) were CPU independent and required a chipset or other controller to interface, and that's where the complexity started to take off.