add vale, work on yosys4gal

.vale.ini

@@ -0,0 +1,18 @@
+StylesPath = styles
+
+MinAlertLevel = suggestion
+
+Packages = write-good
+
+[*.{md}]
+# ^ This section applies to only Markdown files.
+#
+# You can change (or add) file extensions here
+# to apply these settings to other file types.
+#
+# For example, to apply these settings to both
+# Markdown and reStructuredText:
+#
+# [*.{md,rst}]
+BasedOnStyles = Vale, write-good
+

content/blog/yosys4gal/yosys4gal.md

@@ -4,40 +4,66 @@ description: Bringing modern synthesis to 30-year old technology with Yosys and
 date: 2024-06-14
 ---
 
-## A History Lesson
+## A history lesson
 
-During the semiconductor revolution, a dilemma appeared: Designing new ICs required a lot of time and effort to create the mask,
+During the semiconductor revolution, a dilemma appeared: Designing new ICs
-and iteration was expensive. At the time, IC designs were very simple, since the available tools/compute to do tasks like optimization
+required a lot of time and effort to create the mask, and iteration was
-or place-and-route were limited. And what if you wanted a low-volume design? Programmable Logic Arrays (PLAs) were an early
+expensive. At the time, IC designs were very simple, since the available
-approach to these problems. The idea was simple: create a flexible logic archiecture that could be modified later in the process
+tools/compute to do tasks like optimization or place-and-route were limited.
-to implement various digital designs. These worked by using matricies of wires in a Sum-of-Products architecture. Inputs
+And what if you wanted a low-volume design? Programmable Logic Arrays (PLAs)
-would be fed with their normal and inverted forms to a bank of AND gates, which would select various inputs
+were an early approach to these problems. The idea was simple: create a
-using a fuse tie on the die and create product terms. The outputs of the AND gates would then be fed into OR gates, which would 
+flexible logic architecture that could be modified later in the process to
-create the sum term for the whole output.
+implement various digital designs. These worked by using matrices of wires in a
+Sum-of-Products architecture. Inputs would be fed with their normal and
+inverted forms to a bank of AND gates, which would select various inputs using
+a fuse tie on the die and create product terms. The outputs of the AND gates
+would then be fed into OR gates, which would create the sum term for the whole
+output.
 
-This design was popular, since it allowed for less-certain aspects of the chip to be moved to a later design process.
+This design was popular, since it allowed for less-certain aspects of the chip
-Eventually, hardware people got jealous of the fast (for the time) compile-evaluate loops in software, and so PAL (Programmable
+to be moved to a later design process. Eventually, hardware people got jealous
-Array Logic) was invented. These are similar to PLA logic, but the fuses are programmed using a simple programmer rather
+of the fast (for the time) compile-evaluate loops in software, and so PAL
-than a complex die process. This means that a developer with a pile of chips can program one, test it, make some adjustments,
+(Programmable Array Logic) was invented. These are similar to PLA logic, but
-and then program the next. Later versions would solve the whole one-time-programmable aspect using UV-erasable EEPROM.
+the fuses are programmed using a simple programmer rather than a complex die
+process. This means that a developer with a pile of chips can program one, test
+it, make some adjustments, and then program the next. Later versions would
+solve the whole one-time-programmable aspect using UV-erasable EEPROM.
 
-Demands would increase futher and flip-flops would be added, as well as feedback capability. This allows for very complex
-functions to be implemented, since you can chain "rows" of the output blocks.
 
 ![A figure shows the structure of a PLA. There is a grid of wires that is fed into the inputs of AND gates. The AND gates are then selected by a set of OR gates.](pla_logic2.svg "Old School PLA.")
 
+Demands would increase further and flip-flops would be added, as well as
+feedback capability. This allows for very complex functions to be implemented,
+since you can chain "rows" of the output blocks. This culminated in the
+GAL22V10, which was an electronically-erasable, 22-pin programmable logic
+block, which had up to 10 outputs that could be registered and used for
+feedback.
+
+![A figure shows the Output Logic Macrocell, or OLMC. The OLMC consists of a D Flip-Flop, feedback routing, and 4-to-1 mux to select behavior](gal_olmc.png)
+
 ## Back To Today: GALs in the 21st Century
 
-These days, modern FPGA technology can be yours for a couple of bucks. Open-source toolchains allow fast, easy development,
+These days, modern FPGA technology can be yours for a couple of bucks.
-and the glut of Verilog resources online makes it easier than ever to enter the world of hardware design.
+Open-source toolchains allow fast, easy development, and the glut of Verilog
-But there are times when GALs might still be useful. For one, they start up instantly. Some FPGAs have a very fast one-time-
+resources online makes it easier than ever to enter the world of hardware
-programmable internal ROM, but this is obviously not without drawback since the design can no longer change. In most
+design. But there are times when GALs might still be useful. For one, they
-cases the bitstream must be loaded from an external SPI flash. This can take a few seconds, which may not be acceptable if
+start up instantly. Some FPGAs have a very fast one-time- programmable internal
-the logic is critical. Another important factor is the DIP package that is offered. This makes GALs perfect for breadboard
+ROM, but this loses the "field-programmable" aspect which makes FPGAs
-applications. You could use it like an 8-in-1 74-series logic chip, changing the function depending on what you need.
+desirable. In most cases the bitstream must be loaded from an external SPI
-Finally, operating at 5 volts is useful when interfacing with older systems.
+flash. This can take up to a few seconds, which may not be acceptable if the
+logic is critical. Another important factor is the chip packaging. Most FPGAs
+are BGA packages, with some offering QFN or even a few QFP variants, but none
+are available in any DIP form factor, at least without a small board in
+between. The ATF22V10 (which is a clone/successor of the GAL22V10) is available
+in DIP, SSOP, and even PLCC if that's your jam. The package options make GALs
+perfect for breadboard applications. You could use it like an 8-in-1 74-series
+logic chip, changing the function depending on what you need. Additionally,
+GALs operate at 5 volts is useful when interfacing with older systems and
+removes the need for a level shifter.
 
-But programming GALs is an excersize in frustration. Take a look at a basic combinitoral assembly file:
+
+However, this isn't all great. Programming GALs is an exercise in frustration.
+Take a look at a basic combinatorial assembly file:
 
 ```PALASM
 GAL16V8
@@ -61,21 +87,25 @@ DESCRIPTION
 Simple test of combinatorial logic.
 ```
 
-While it's pretty intuititve what it does, it's not exactly a stellar format for writing complex logic.
+In the contrived example the behavior is pretty clear, but it's not exactly a
-Plus, there's no way to integrate or test this (we'll get back to this). Compared to the Verilog flow,
+stellar format for writing complex logic. Plus, there's no way to integrate or
-with simulation, testbenches, and synthesis, the raw assembly is stuck in the 80s.
+test this in a larger system (we'll get back to this). Compared to the Verilog
+flow, with simulation, testbenches, and synthesis, the raw assembly is stuck in
+the 80s and requires manual logic simplification.
 
-Verilog compilers for GALs *did exist*, but they ran on old-as-dirt systems, didn't have any significant optimization
+Verilog compilers for GALs *did exist*, but they ran on old-as-dirt systems,
-capabilities, and were almost always proprietary. What if we could make our own open-source Verilog flow for GAL chips?
+didn't have any significant optimization capabilities, and were almost always
-Then we could write test benches in Verilog, map complex designs onto the chip, and even integrate our designs with FPGAs later
+proprietary. What if we could make our own open-source Verilog flow for GAL
-down the line.
+chips? Then we could write test benches in Verilog, map complex designs onto
+the chip, and even integrate our designs with FPGAs later down the line.
 
 
+# The idea
+
+GAL assembly is still common
 
 # Is this useful?
 
-# using menu screens
-
 No, not really.
 
 Well, there's a very very niche use case. These parts are 5-volt tolerant, and come in DIP packages. If you needed some basic glue logic

flake.nix

@@ -18,6 +18,7 @@
 		packages = forAllSystems (pkgs: rec {
 			default = pkgs.buildNpmPackage {
 				name = "myblog";
+				version = "unstable";
 				buildInputs = with pkgs; [
 					nodejs
 					vips