Sunday, June 3, 2018

Emulating Amstrad PC1512

My first computer was Amstrad Schneider PC1512SD  so it's understandable that I'm attached to that computer. I own two of them but since lately I don't have enough time to play with them I started to search for emulators to be able to try from time to time old software and games I've used. Since I lost some time to figure out how to emulate Amstrad, I decided to document everything in this blog post. This should be useful to me when I decide I want to play with it again in the future, but it can also help anyone else following my footsteps.

First I needed to find PC XT emulator. Modern day emulators/virtualization solutions like Qemu, VirtualBox, VMWare, and even Bochs do not support anything older than Pentium. So, some other emulator has to be used. After some time spending searching for XT emulators I found the following candidates:
  1. MAME
  2. PCem
  3. PCjs
Turns out MAME and PCem support Amstrad PC1512 while PCjs doesn't. So I decided to go with PCem and MAME. After some trying I didn't manage to get anything from PCem. Namely, after starting emulation the screen was completely garbled so I decided to try MAME. I spent some time trying to figure out how to emulate Amstrad using MAME. Here is the essence of it on Fedora 27:
  1. First, you need to install mame package. This package is present in Fedora repository so except of 'dnf install mame' no additional configuration is necessary.
  2. Next, you need to obtain ROM images from Amstrad. After some (actually a lot of) Googling I managed to find them. If I remember correctly, I obtained them via MAME ROMS package.
ROMs that you should have are any of the following three ones:
  1. Version 1 ROMs: 40044.ic132 (8kB, SHA1: 7781d4717917262805d514b331ba113b1e05a247) and 40043.ic129 (8kB, SHA1: 74002f5cc542df442eec9e2e7a18db3598d8c482)
  2. Version 2 ROMs: 40044v2.ic132 (8kB, SHA1: b12fd73cfc35a240ed6da4dcc4b6c9910be611e0) and 40043v2.ic129 (8kB, SHA1: c376fd1ad23025081ae16c7949e88eea7f56e1bb)
  3. Version 3 ROMs: 40044-2.ic132 (8kb, SHA1: b77fa44767a71a0b321a88bb0a394f1125b7c220) and 40043-2.ic129 (8kB, SHA1: 18a17b710f9eb079d9d7216d07807030f904ceda).
The names are as expected by MAME. In addition there'll be some other ROMs too:
  1. 40045.ic127 (8kb, SHA1: 7d858bbb2e8d6143aa67ab712edf5f753c2788a7)
  2. 40078.ic127 (8kB, SHA1: bc8dc4dcedeea5bc1c04986b1f105ad93cb2ebcd)
  3. wdbios.rom (8kB, SHA1: 601d7ceab282394ebab50763c267e915a6a2166a)
The first two are, I believe, fonts while the third one is necessary only if you want to emulate HD version of PC1512.

Create in the current (working) directory folder named pc1512 and place selected ROMs into it.

We can now start emulator. Use the following command line:
$ mame pc1512 -rompath . -window -uimodekey DEL_PAD
The first argument to MAME emulator is machine that should be emulated, in our case its PC1512. The option rompath instructs MAME to search for ROMs in the current directory. In our case it'll search for folder named pc1512 and within it for ROMs names as given above. The the option window prevents MAME from going fullscreen (and I had some problems exiting). Finally, the option uimodekey defines escape key to access internal menu.

This will give famous "Pleas wait..." message from BIOS and then "Insert SYSTEM disk into drive A" message. Now we are at the point of providing boot disks to the emulated machine. For that it is necessary to obtain images of Amstrad PC1512 disks. You can find them here. The problem is that disks 1 and 4 are given in CFI format (Compressed Floppy Image, created by tool FDCOPY.COM), while disks 2 and 3 are archives.

So, after unpacking disk 1 (46001.Zip) and disk 4 (46004.Zip) you are presented with files 46001.CFI and 46004.CFI which are not recognized by MAME. To convert them into appropriate format use the following command:
dsktrans -itype cfi 46001.cfi 46001.dsk
dsktrans is a tool that is part of libdsk-tools package, also part of the Fedora repository. So, just run 'dnf install libdsk-tools' and that should be it. After converting 1st disk you can also convert 4th disk.

Now, we are ready to start MAME with system disk provided. One way to do that is to open internal MAME menu after staring PC1512 and then attaching disk image. The other way is to use command line:
mame pc1512 -rompath . -window -uimodekey DEL_PAD -flop 46001.dsk
The new option is flop that defines image to be used as a floppy in a floppy disk. By the way, to find out supported floppies you can use the following command:
mame pc1512 -listmedia
and take a note of (brief) column.

What happens now is that you are provided with MS DOS command prompt in emulated machine.

The next step is to start GEM, but before that I have to find out how to create floppy disk image. Note that the tools imgtool that is part of MAME gives segmentation fault on almost any command you try. Anyway, stay tuned for GEM...

Some useful resources I found while working on this:

Wednesday, August 30, 2017

Difference between command substitution and 'while read' in bash

I just changed one of my scripts that, in principle, looked like this:
for i in `find . -type d`
     # do some processing on the found directory
The new format I use is:
find . -type d | while read i
    # do some processing on the found directory
While both versions will work in general, the second variant is better for the following reasons:
  1. It's faster. Namely, in the first case the find command has to finish before processing on directories starts. This isn't noticeable for small directory hierarchies, but it becomes very noticeable for large ones. In the second case the find command outputs results and in parallel while loop picks them up and does processing.
  2. In case you have spaces embedded in directory names, the second version will work, while the first won't.
Maybe there are some other advantages (or disadvantages) of the second version, but none I can remember at the moment. If you know any, please write it in the comments!

Tuesday, August 22, 2017

Viber and Fedora 26 SSL errors

I just downloaded and updated Viber on my Fedora. When I tied to start it, it seg faulted with the following errors:
QSqlDatabasePrivate::removeDatabase: connection 'ConfigureDBConnection' is still in use, all queries will cease to work.
Qt WebEngine ICU data not found at /opt/viber/resources. Trying parent directory...
Qt WebEngine resources not found at /opt/viber/resources. Trying parent directory...
Qt WebEngine ICU data not found at /opt/viber/resources. Trying parent directory...
Qt WebEngine resources not found at /opt/viber/resources. Trying parent directory... QSslSocket: cannot resolve CRYPTO_num_locks QSslSocket: cannot resolve CRYPTO_set_id_callback QSslSocket: cannot resolve CRYPTO_set_locking_callback QSslSocket: cannot resolve ERR_free_strings QSslSocket: cannot resolve EVP_CIPHER_CTX_cleanup QSslSocket: cannot resolve EVP_CIPHER_CTX_init QSslSocket: cannot resolve sk_new_null QSslSocket: cannot resolve sk_push QSslSocket: cannot resolve sk_free QSslSocket: cannot resolve sk_num QSslSocket: cannot resolve sk_pop_free QSslSocket: cannot resolve sk_value QSslSocket: cannot resolve SSL_library_init QSslSocket: cannot resolve SSL_load_error_strings QSslSocket: cannot resolve SSL_get_ex_new_index QSslSocket: cannot resolve SSLv23_client_method QSslSocket: cannot resolve SSLv23_server_method QSslSocket: cannot resolve X509_STORE_CTX_get_chain QSslSocket: cannot resolve OPENSSL_add_all_algorithms_noconf QSslSocket: cannot resolve OPENSSL_add_all_algorithms_conf QSslSocket: cannot resolve SSLeay QSslSocket: cannot resolve SSLeay_version QSslSocket: cannot call unresolved function CRYPTO_num_locks QSslSocket: cannot call unresolved function CRYPTO_set_id_callback QSslSocket: cannot call unresolved function CRYPTO_set_locking_callback QSslSocket: cannot call unresolved function SSL_library_init QSslSocket: cannot call unresolved function SSLv23_client_method QSslSocket: cannot call unresolved function sk_num
Segmentation fault (core dumped)
After some digging the solution was simple, just execute the following command and it should work afterwards:
sudo ln -s /usr/lib64/ /opt/viber/lib/

About Me

scientist, consultant, security specialist, networking guy, system administrator, philosopher ;)