The 8049 is connected to an Arduino instead of the 6802 Nano Computer.

I used the same method, with two differences: There is a web page called 8049 Spy that explains how to connect the 8049 for reading the ROM. Will they contain the same or different code? I also got a second QL 8049 to use in my initial experiments and avoid the risk of ruining the chip in my QL. I bought an Arduino UNO board to connect it to the 8049 and read the ROM. Reading the ROM can be accomplished by using the 'ROM Verification Algorithm' described in the MCS-48 datasheet (MCS-48 is the family of microcontrollers that includes the 8049). To compare the speed measured on a real QL to the emulation speed, I need to be sure about what code is running on the IPC, so I decided to dump the contents of the chip and compare them to the version from the internet.ĮPROM programmers have the circuitry necessary to read the 8049 ROM, but I don't know of any programmers that support this chip, probably because it cannot be written to.

In order to improve the 'QL Speed' accuracy of Q-emuLator, I plan to better account for the 8049 timings (simulating the interaction between the 68008 andthe ZX8301 ULA will also be necessary, but that's a topic for another day). There are a few copies of the QL IPC code on the internet and they are all the same, apart for a single unused byte toward the end of the ROM. This also means that if you need to replace an IPC chip, you cannot just buy any available 8049: It needs to come from a QL, or it will contain a different, incompatible ROM. Sinclair wrote the code, but it got programmed in the chip by the manufacturer, and there is no way to reprogram it. The code is stored in an internal 2 KB ROM.

This can cause a significant slowdown of QL software and the exact timing depends on the code that runs on the IPC. Communication between the 60008 and IPC uses a slow serial link and can only happen when the IPC is in-between activities like scanning the keyboard or producing the next segment of a sound.

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