Tag: IBM Assembler

I’ve updated the article about LAY to include how to decrement a register with LAY. If you haven’t seen this before, it’s worth a look. Read about LAY here.

In my spare time, I entertain myself by writing a series of mystery novels. The first novel was The Elvis Bird, and the most recent is Death of a Golden Bird. They are about a southern ornithologist who researches birds (The Ivory-billed Woodpecker and the Golden Eagle) and stumbles over murders. Both novels are available on Amazon in paper and Kindle. These days, I am working on a third novel in the series. You can read more about them at dewoolbright.com .

If you would like to support this site and make an old but budding novelist happy, consider buying copies. As always, thanks for using the site.

David Woolbright

One thing that’s great about learning IBM assembler is that if you master one instruction, you often learn a handful of others by association. That’s the case with AGSI – Add Grande Storage Immediate, which is related to ASI. The G in AGSI suggests a register might be involved, but don’t be fooled. Both operands are in storage. The first operand is eight bytes – the size of a grande register,the second operand is a single immediate constant that occupies the second byte of the instruction. Get the details here. Watch the instruction in action with Visiblez here.

This little instruction comes with two surprises. I’ll tell you about one: It allows us to add two binary fields without a register! We could always add two packed fields without a register, but now we can do that with 2’s complement fields in memory. You’ll have to watch the ASI video to learn the other surprise.

So, have a cup of coffee, and review this humble but interesting little instruction.

Read about ASI here. Watch the Visiblez video here.

I’m creating new articles on my website in alphabetical order, and I’m on the A’s. There are numerous add instructions to choose from. Today’s instruction is AGF and is similar to AGI which we have already reviewed. You can find the writeup here, and you can watch the instruction in action using Visiblez here.

With hundreds of instructions to choose from, it never hurts to review one. Get my take on Add Grande (AG) with this write-up. You can watch a short video of this instruction in action here.

With hundreds of instructions to use, it never hurts to review one. Get my take on Add Fullword Immediate (AFI) with this write-up. You can watch a short video of this instruction in action here.

1. Find out the model z machine you are using.
2. Go here: https://www.ibm.com/docs/en/systems-hardware/zsystems
3. Click on your model.
4. Choose Related Publications twice.
5. Scroll to z/Architecture Principles of Operation
6. Bookmark it.

You will also get a link for the z/Architecture Reference Summary that contains all the machine instruction formats, a listing of all instructions by mnemonic, and all sorts of details about the machine architecture.

There are several new videos and PPTs that introduce macros and conditional assembly that can now be found in the Video Course link. These videos were lost and I am reposting them. You can also find them at the following links:

• Conditional Assembly and Macros (MP4)(PPT)
• Macro Lecture 2 (MP4)
• Macro Lecture Demo (MP4)

I look forward to attending the IBM TechXchange Conference in Las Vegas, Oct 21-24. I hope to see some of you there. You can learn about the conference and register here:

https://www.ibm.com/community/ibm-techxchange-conference