IBM 704 memory size initialized to 16Ki

[diyessi]

• Context

  In I7000/i7090_cpu.c the memory size is initialized to 16Ki. If you start BIN/i704 and type show cpu it will report

  CPU     
      704, 32K

  but if you enter

  sim> d -m 0 lxa 0,4
  sim> d -m 1 txi 1,4,77777
  sim> step
  sim> step
  sim> e xr[4]
  XR[4]:  37777

  indicating 16Ki.

If you first

sim> set cpu 32k

and repeat the two instructions, you will correctly get 77777.

The problem is related to https://github.com/open-simh/simh/blob/2396fd03499af3d01cf637b3e04409dc25572d2f/I7000/i7090_cpu.c#L305 and goes away if you change the 4 to a 5 and get rid of the memory size halving in the next line, but I don't know what the implications of that would be on other processors.

BTW, 704s were only available in 4Ki, 8Ki and 32Ki according to the manual of operation on bitsavers.

• the output of "sim> SHOW VERSION" while running the simulator which is having the issue

IBM 704 simulator Open SIMH V4.1-0 Current Simulator Framework Capabilities: 64b data 32b addresses Threaded Ethernet Packet transports:PCAP:VDE:NAT:UDP Idle/Throttling support is available Virtual Hard Disk (VHD) support RAW disk and CD/DVD ROM support Asynchronous I/O support (Lock free asynchronous event queue) Asynchronous Clock support FrontPanel API Version 12 Host Platform: Compiler: GCC Apple LLVM 15.0.0 (clang-1500.0.40.1) Simulator Compiled as C arch: x64 (Debug Build) on Nov 26 2023 at 21:35:56 Build Tool: CMake (Ninja) Memory Access: Little Endian Memory Pointer Size: 64 bits Large File (>2GB) support SDL Video support: No Video Support PCRE RegEx (Version 8.45 2021-06-15) support for EXPECT commands OS clock resolution: 1ms Time taken by msleep(1): 1ms Ethernet packet info: libpcap version 1.10.1 OS: Darwin Cuyamaca.local 23.1.0 Darwin Kernel Version 23.1.0: Mon Oct 9 21:27:27 PDT 2023; root:xnu-10002.41.9~6/RELEASE_X86_64 x86_64 Processor Name: Intel(R) Core(TM) i7-8700B CPU @ 3.20GHz tar tool: bsdtar 3.5.3 - libarchive 3.5.3 zlib/1.2.12 liblzma/5.0.5 bz2lib/1.0.8 curl tool: curl 8.1.2 (x86_64-apple-darwin23.0) libcurl/8.1.2 (SecureTransport) LibreSSL/3.3.6 zlib/1.2.12 nghttp2/1.55.1 git commit id: 2396fd03 git commit time: 2023-11-15 20:36:10-05:00

• how you built the simulator or that you're using prebuilt binaries

ninja

[rcornwell]

Will look into this. I have a bunch of patches for my I7000 simulators pending final checks that they are working correctly. I will check this one out as well.

[diyessi]

memmask is initialized to 077777 but cpu_reset sets it to MEMMASK which is initialized to 037777.

[rcornwell]

Thanks, was simple fix. In cpu_reset the memmask = MEMSIZE - 1; I will try and get fixes out today.